New York — The head of New York City's beleaguered Homeless Services agency is stepping down amid a stubborn rise in homelessness that has become a significant political problem for Mayor Bill de Blasio.

Gilbert Taylor, who was appointed commissioner of the Department of Homeless Services when de Blasio took office in January 2014, announced Tuesday he is resigning his post at year's end. His sudden departure comes as part of an overhaul of the department that has struggled to combat the rise in homelessness in the nation's largest city.

"Tackling homelessness is an urgent priority," de Blasio said in a statement announcing a comprehensive review of the department. "We must also guarantee that the organizational structure is best positioned to deliver these services and operate these programs."

Nearly 58,000 people are living in New York's homeless shelters, according to statistics released by the city this week. More than 23,000 of them are children. An additional 3,000 or so people are estimated to be living on the city's streets.

The numbers are down slightly from a peak last winter but still up from when de Blasio took office. His critics have seized upon the rise as evidence that the mayor's liberal policies are failing those who need the most help.

Some highly visible examples of homelessness have become a regular sight in the city's tabloids and on local TV newscasts, and a poll released last month showed that nearly two-thirds of New Yorkers disapproved of how de Blasio has handled the issue. The mayor's overall approval ratings have also sunk, now topping out in the low 40s in several recent polls.

Moreover, it's become the latest front in the ongoing cold war between de Blasio and Gov. Andrew Cuomo, who has suggested that the state will intervene to manage the problem because the city hasn't been able to.

Mayoral aides have touted the steps the city has taken to manage the issue, including a $2.6 billion investment to pay for the creation of 15,000 "supportive housing" units for the homeless — apartments that will be paired with on-site social services to help domestic abuse victims, veterans, drug addicts and those living on the street. The city has also repaired dozens of shelters, cleaned up unsafe homeless encampments and created beds for the homeless in houses of worship.

De Blasio said Human Resources Administration Commissioner Steve Banks and First Deputy Mayor Anthony Shorris will lead the review of the Department of Homeless Services. Taylor is the second major departure of an official overseeing homelessness in New York City. Deputy Mayor Lilliam Barrios Paoli departed in August.

"There is never a good time to leave a position such as this one," said Taylor in a statement. "I feel good about how far I have been able to advance the work of this agency and committed to working with this administration to assist with this transition."